The disinfection of liquids, in particular of drinking water or waste water with UV radiation, has been known for a long time. For this purpose the liquid, to be disinfected, is ducted in an open or closed channel. For effective disinfection it is essential that each volume element of the liquid flow receives a certain minimum dosage of UV radiation. Since on the other hand the energy consumption of UV disinfection equipment is an important criterion for the particular operating efficiency, radiation power which is not excessively high is to be used. It is therefore crucial that the liquid flow is so well mixed that each volume element receives the same radiation dosage and no flow paths, in which the radiation dosage is too little, are created.
Various solutions for this are known from the prior art. On the one hand there is disinfection equipment, wherein longitudinally extending UV irradiators are arranged lengthwise in the channel in the flow direction, so that the liquid flow is parallel to the longitudinal axis of the irradiators. In the case of this configuration a uniform spread of the irradiators over the cross section is to be maintained. In addition baffle plates which are located in front of the irradiators or on the irradiators are fitted in the free cross section of the device. These baffle plates create a turbulent current, which diverts volume elements from the centre of the free flow cross section and brings them into proximity of the surface of the irradiators.
Also, disinfection equipment, in which the longitudinal axis of the irradiators is arranged transverse to the flow direction, is known. In the case of this equipment the irradiators themselves create a turbulent current. The individual volume elements of the liquid to be treated are forced through the gap developing between two adjacent irradiators and behind it flow into a wider free cross section up to the next row of UV irradiators. This change in cross section already causes thorough mixing.
Finally, it is known, in front of the disinfection devices, to position a weir or barrage over which the water to be treated must flow. A large turbulence, which should guarantee good mixing of the liquid to be treated, is also created here.
All devices of the type specified above are passive, that is to say, they use the genetic energy of the flowing liquid to create the turbulence. This inevitably leads to an increase in the dynamic resistance or dynamic pressure, which builds up in front of the disinfection device. This is particularly disadvantageous where the liquid to be treated flows purely due to the downward gradient in an existing environment. This is regularly the case particularly with sewage treatment works, in which only a limited downward gradient between an inflow and an outflow is present. If this downward gradient is not sufficient, it becomes necessary to circulate the waste water to be treated by pumps. This is costly.